Serum Cytokines and Growth Factors in Subjects with Type 1 Diabetes: Associations with Time in Ranges and Glucose Variability

Cytokine Signaling in Diabetic Neuropathy: A Key Player in Peripheral Nerve Damage

Diabetic peripheral neuropathy (DPN) is a debilitating complication of diabetes mellitus, characterized by progressive nerve damage driven by chronic hyperglycemia and systemic inflammation. The pathophysiology of DPN is significantly influenced by pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α. These cytokines promote oxidative stress, vascular dysfunction, and neuronal degeneration by activating important signaling pathways including NF-κB and MAPK. While IL-6 promotes a pro-inflammatory microenvironment, increasing neuronal damage and neuropathic pain, TNF-α and IL-1β worsen Schwann cell failure by compromising axonal support and causing demyelination. Immune cell infiltration and TLR activation increase the inflammatory cascade in DPN, resulting in a persistent neuroinflammatory state that sustains peripheral nerve injury. The main characteristics of DPN are axonal degeneration, decreased neurotrophic support, and Schwann cell dysfunction, which weaken nerve transmission and increase susceptibility to damage. Advanced glycation end-products, TNF-α, and CXCL10 are examples of biomarkers that may be used for early diagnosis and disease progression monitoring. Additionally, crucial molecular targets have been found using proteomic and transcriptome techniques, enabling precision medicine for the treatment of DPN. This review emphasizes the importance of cytokine signaling in the pathogenesis of DPN and how cytokine-targeted treatments might reduce inflammation, restore nerve function, and improve clinical outcomes for diabetic patients.

Identification of crucial extracellular genes as potential biomarkers in newly diagnosed Type 1 diabetes via integrated bioinformatics analysis

Purpose

In this study, we aimed to study the role of extracellular proteins as biomarkers associated with newly diagnosed Type 1 diabetes (NT1D) diagnosis and prognosis.

Patients and Methods

We retrieved and analyzed the GSE55098 microarray dataset from the Gene Expression Omnibus (GEO) database. Using R software, we screened out the extracellular protein-differentially expressed genes (EP-DEGs) through several protein-related databases. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were applied to describe the role and function of these EP-DEGs. We used the STRING database to construct the interaction of proteins, Cytoscape software to visualize the protein-protein interaction (PPI) networks, and its plugin CytoHubba to identify the crucial genes between PPI networks. Finally, we used the comparative toxicogenomics database (CTD) to evaluate the connection between NT1D with the potential crucial genes and we validated our conclusions with another dataset (GSE33440) and some clinical samples.

Results

We identified 422 DEGs and 122 EP-DEGs from a dataset that includes (12) NT1D patients compared with (10) healthy people. Protein digestion and absorption, toll-like receptor signaling, and T cell receptor signaling were the most meaningful pathways defined by KEGG enrichment analyses. We recognized nine important extracellular genes: GZMB, CCL4, TNF, MMP9, CCL5, IFNG, CXCL1, GNLY, and LCN2. CTD analyses showed that LCN2, IFNG, and TNF had higher levels in NT1D and hypoglycemia; while TNF, IFNG and MMP9 increased in hyperglycemia. Further verification showed that LCN2, MMP9, TNF and IFNG were elevated in NT1D patients.

Conclusion

The nine identified key extracellular genes, particularly LCN2, IFNG, TNF, and MMP9, may be potential diagnostic biomarkers for NT1D. Our findings provide new insights into the molecular mechanisms and novel therapeutic targets of NT1D.

IL-20RA is Associated with the Risk of Diabetic Microangiopathy: A Bidirectional Mendelian Randomization Analysis and Clinical Validation

Objective

Studies have demonstrated a link between chronic inflammatory responses and diabetic microangiopathy, which include diabetic nephropathy, diabetic retinopathy, and diabetic neuropathy. However, it remains unclear whether there is a causal association between circulating inflammatory cytokines and the development of diabetic microvascular complications. This study aimed to investigate whether altered genetically predicted concentrations of circulating inflammatory cytokines were associated with the development of diabetic microvascular complications using two-sample Mendelian randomization (MR) analysis and clinical validation.

Methods

Pooled data on diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and 91 circulating inflammatory cytokines were obtained from publicly available databases. The analysis was conducted mainly using the inverse variance weighting (IVW) method and the results were assessed based on the odds ratio (OR) and 95% confidence interval (CI). In addition, the stability and reliability of the results were verified using the leave-one-out method, heterogeneity tests, and horizontal pleiotropy. Finally, ELISA and RT-qPCR were utilized to assess the expression of relevant inflammatory cytokines associated with diabetic microvascular complications.

Results

Mendelian randomization analysis identified a total of 9 circulating inflammatory cytokines that exhibit causal associations with the diabetic microangiopathy, with IL-20RA being a common risk factor for all three conditions. Clinical studies have found elevated plasma IL-20RA concentrations in patients with diabetic peripheral neuropathy, and RT-qPCR testing of peripheral blood mononuclear cells revealed significantly higher IL-20RA mRNA expression in patients with diabetic peripheral neuropathy as compared to normal individuals.

Conclusion

This study highlights the potential role of specific inflammatory cytokines in the development of diabetic microangiopathy (diabetic nephropathy, diabetic retinopathy and diabetic neuropathy). Additionally, IL-20RA emerges as a potential common risk factor for three diabetic microvascular complications. These findings may provide novel insights into early prevention and new therapeutic strategies for diabetic microvascular complications.

Serum and urinary levels of MIF, CD74, DDT and CXCR4 among patients with type 1 diabetes mellitus, type 2 diabetes and healthy individuals: Implications for further research

Background

Macrophage migration inhibitory factor (MIF) is a highly conserved cytokine with pleiotropic properties, mainly pro-inflammatory. MIF seems to exert its pro-inflammatory features by binding to its transmembrane cellular receptor CD74. MIF also has CXCR4, which acts as a co-receptor in this inflammatory process. Apart from MIF, D-dopachrome tautomerase (DDT) or MIF2, which belongs to the MIF superfamily, also binds to receptor CD74. Therefore, these molecules, MIF, CD74, DDT and CXCR4 are suggested to work together orchestrating an inflammatory process. Diabetes mellitus is characterised by chronic low-grade inflammation. Therefore, the aim of the present study was to evaluate serum and urinary levels of the aforementioned molecules among patients with type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM) and among healthy controls.

Methods

We enrolled 13 patients with T1DM, 74 patients with T2DM and 25 healthy individuals as controls. Levels of CD74, CXCR4, DDT, and MIF were measured using ELISA Kits according to the manufacturer's instructions.

Results

We documented increased serum MIF levels together with higher urinary CD74 levels among patients with T1DM, when compared to patients with T2DM and healthy adults. In particular, patients with T1DM showed significantly increased levels of MIF compared to T2DM (p = 0.011) and healthy controls (p = 0.0093). CD74 in urine were significantly higher in patients with T1DM compared to those affected with T2DM (p = 0.0302) and healthy group (p = 0.0099). On the contrary, serum CD74 were similar among the three groups. No statistical differences were identified in CXCR4 levels both in serum and in urine of all groups. Patients with T2DM and overweight/obesity had increased urinary levels of CD74, when compared to lean patients with T2DM.

Conclusion

The increased serum MIF levels and urinary CD74 levels among patients with T1DM may be attributed to the autoimmune milieu, which characterises patients with T1DM, when compared to patients with T2DM. These two findings merit further attention as they could pave the way for further research regarding the potential beneficial effects of inhibitors of MIF among patients with T1DM, especially in the early stages of T1DM. Finally, the role of inhibitors of MIF could be further explored in the context of obesity among patients with T2DM.

Decoding the Significance of Alpha Cell Function in the Pathophysiology of Type 1 Diabetes

Alpha cells in the pancreas, traditionally known for their role in secreting glucagon to regulate blood glucose levels, are gaining recognition for their involvement in the pathophysiology of type 1 diabetes (T1D). In T1D, autoimmune destruction of beta cells results in insulin deficiency, which in turn may dysregulate alpha cell function, leading to elevated glucagon levels and impaired glucose homeostasis. This dysfunction is characterized by inappropriate glucagon secretion, augmenting the risk of life-threatening hypoglycemia. Moreover, insulin deficiency and autoimmunity alter alpha cell physiological responses, further exacerbating T1D pathophysiology. Recent studies suggest that alpha cells undergo transdifferentiation and interact with beta cells through mechanisms involving gamma-aminobutyric acid (GABA) signaling. Despite these advances, the exact pathways and interactions remain poorly understood and are often debated. Understanding the precise role of alpha cells in T1D is crucial, as it opens up avenues for developing new therapeutic strategies for T1D. Potential strategies include targeting alpha cells to normalize glucagon secretion, utilizing glucagon receptor antagonists, enhancing GABA signaling, and employing glucagon-like peptide-1 (GLP-1) receptor agonists. These approaches aim to improve glycemic control and reduce the risk of hypoglycemic events in individuals with T1D. This review provides an overview of alpha cell function in T1D, highlighting the emerging focus on alpha cell dysfunction in the context of historically well-developed beta cell research.

Sex-Specific Cytokine, Chemokine, and Growth Factor Signatures in T1D Patients and Progressors

While studies have reported altered levels of cytokines in type 1 diabetes (T1D) patients, the results are inconsistent, likely because of variable factors. This study tests the hypothesis that there are sex-based differences in cytokine levels in T1D, prior to and after disease onset. We analyzed 48 blood cytokine, chemokine, and growth factor levels using a multiplex assay. We found only two cytokines, M-CSF and IL-6, with significant differences between T1D patients (n=25) versus controls overall (n=25). However, we identified notable alterations when comparing sex-age-matched controls and T1D samples. Inflammatory cytokines (TNF-α, IL-6, IL-1a), Th2 cytokines (IL-4, IL-13), and chemokines (MIP-1α, RANTES, MIP-3) were lower in female T1D patients compared to female controls, but not in males. IL-22 was lower in female T1D patients compared to female controls, while it was higher in male T1D patients compared to male controls. In contrast, growth factors (EGF, PDGF-AB/BB) were higher in male T1D patients compared to male controls. In T1D progressors (children who developed the disease years after the sample collection, n=16-21), GROa was lower compared to controls in both sexes. Our findings underscore the importance of understanding sex-specific differences in T1D pathogenesis and their implications for developing personalized treatments.

Glucose Variability in People with Type 1 Diabetes: Associations with Body Weight, Body Composition, and Insulin Sensitivity

The prevalence of overweight and obesity increases in people with type 1 diabetes (T1D). However, the impact of fat accumulation on glucose dynamics in T1D is poorly understood. We assessed continuous glucose monitoring (CGM) parameters in patients with T1D depending on their body weight, body composition, and insulin sensitivity. In 547 patients, including 238 overweight/obese individuals, CGM-derived time in range (TIR) and glucose variability (GV) were estimated. Body composition was assessed by DXA. Estimated glucose disposal rate (eGDR) was used as an indicator of insulin sensitivity. Overweight/obese patients, when compared to normal-weight ones, have a lower time below range (TBR) (<3 mmol/L), GV, and experienced fewer episodes of low glucose. In men, lower TIR, higher time above range (TAR), and GV reduction were associated with central adiposity assessed by total, trunk, and android fat mass. In women, gynoid fat mass only was associated with a lower TIR and higher TAR. The eGDR was a positive predictor of TIR and a negative predictor of TAR, TBR, and GV in men and women. In conclusion, adiposity in people with T1D is associated with a lower risk of CGM-confirmed hypoglycemia, higher TAR, and reduced GV. These features of daily glucose dynamics may be mediated by insulin resistance.

Diabetes-induced muscle wasting: molecular mechanisms and promising therapeutic targets

Diabetes has become a serious public health crisis, presenting significant challenges to individuals worldwide. As the largest organ in the human body, skeletal muscle is a significant target of this chronic disease, yet muscle wasting as a complication of diabetes is still not fully understood and effective treatment methods have yet to be developed. Here, we discuss the targets involved in inducing muscle wasting under diabetic conditions, both validated targets and emerging targets. Diabetes-induced skeletal muscle wasting is known to involve changes in various signaling molecules and pathways, such as protein degradation pathways, protein synthesis pathways, mitochondrial function, and oxidative stress inflammation. Recent studies have shown that some of these present potential as promising therapeutic targets, including the neuregulin 1/epidermal growth factor receptor family, advanced glycation end-products, irisin, ferroptosis, growth differentiation factor 15 and more. This study's investigation and discussion of such pathways and their potential applications provides a theoretical basis for the development of clinical treatments for diabetes-induced muscle wasting and a foundation for continued focus on this disease.

The Role of Cytokines and T Cells as Mediators of Inflammatory Pathology in Type 1 Diabetes and COVID-19

During the coronavirus disease 2019 (COVID-19) pandemic, reports of individuals experiencing new-onset type 1 diabetes (T1D) began to appear in the literature. This spurred subsequent epidemiological studies that demonstrated an increase in new diagnosis of T1D compared to prepandemic. Development of T1D is characterized by the development of an inappropriate T cell response directed against pancreatic beta-cells, leading to eventual loss of insulin secretion. This T cell response occurs in genetically susceptible individuals and may be triggered by viral illnesses. Abnormal cytokine production is another element of the pathogenesis of T1D. Infection with severe acute respiratory syndrome related coronavirus 2 induces a profound increase in the production of inflammatory cytokines and causes significant T-cell dysregulation. These disruptions of the immune system may be linked to the development of T1D following COVID-19. [Pediatr Ann. 2024;53(7):e264-e268.].

Alzheimer's Disease: Models and Molecular Mechanisms Informing Disease and Treatments

Alzheimer's Disease (AD) is a complex neurodegenerative disease resulting in progressive loss of memory, language and motor abilities caused by cortical and hippocampal degeneration. This review captures the landscape of understanding of AD pathology, diagnostics, and current therapies. Two major mechanisms direct AD pathology: (1) accumulation of amyloid β (Aβ) plaque and (2) tau-derived neurofibrillary tangles (NFT). The most common variants in the Aβ pathway in APP, PSEN1, and PSEN2 are largely responsible for early-onset AD (EOAD), while MAPT, APOE, TREM2 and ABCA7 have a modifying effect on late-onset AD (LOAD). More recent studies implicate chaperone proteins and Aβ degrading proteins in AD. Several tests, such as cognitive function, brain imaging, and cerebral spinal fluid (CSF) and blood tests, are used for AD diagnosis. Additionally, several biomarkers seem to have a unique AD specific combination of expression and could potentially be used in improved, less invasive diagnostics. In addition to genetic perturbations, environmental influences, such as altered gut microbiome signatures, affect AD. Effective AD treatments have been challenging to develop. Currently, there are several FDA approved drugs (cholinesterase inhibitors, Aß-targeting antibodies and an NMDA antagonist) that could mitigate AD rate of decline and symptoms of distress.

Targeting IL-12 family cytokines: A potential strategy for type 1 and type 2 diabetes mellitus

Diabetes is a common metabolic disease characterized by an imbalance in blood glucose levels. The pathogenesis of diabetes involves the essential role of cytokines, particularly the IL-12 family cytokines. These cytokines, which have a similar structure, play multiple roles in regulating the immune response. Recent studies have emphasized the importance of IL-12 family cytokines in the development of both type 1 and type 2 diabetes mellitus. As a result, they hold promise as potential therapeutic targets for the treatment of these conditions. This review focuses on the potential of targeting IL-12 family cytokines for diabetes therapy based on their roles in the pathogenesis of both types of diabetes. We have summarized various therapies that target IL-12 family cytokines, including drug therapy, combination therapy, cell therapy, gene therapy, cytokine engineering therapy, and gut microbiota modulation. By analyzing the advantages and disadvantages of these therapies, we have evaluated their feasibility for clinical application and proposed possible solutions to overcome any challenges. In conclusion, targeting IL-12 family cytokines for diabetes therapy provides updated insights into their potential benefits, such as controlling inflammation, preserving islet β cells, reversing the onset of diabetes, and impeding the development of diabetic complications.